While standing on a skateboard, a person can propel themselves and/or modify course of direction with a paddle, comprising a shaft, handle and pusher tip. Pusher tips are generally mounted to a distal end of an axially symmetrical paddle shaft such that the pusher tip can be positioned in contact with the ground during use. In particular, a user can push off or grip the ground with the pusher tip by extending the paddle shaft while remaining on a skateboard or roller skates.
Some pusher tips can define a substantially spherical shape with a planar surface and include an opening into which the distal end of the paddle shaft is secured. Such pusher tips can conform to the surface of the ground and mostly roll with the paddle shaft movement. However, such pusher tips generally cannot support bending moment on the distal end of the paddle shaft, resulting in a bouncy feeling at the distal end of the paddle shaft, and fail to provide flexibility near the connection to the paddle shaft due to the insertion of the distal end of the paddle shaft into the pusher tip body.
Some pusher tips can include a base section, a top section and a flexible central section connecting the base and top sections. The base section can grip the ground without rolling and the angle of the top section can vary by flexing the flexible central section with the paddle shaft. However, such pusher tips generally cannot support bending moment on the paddle shaft distal end, and collapse, buckle or let go of the ground part way through a stroke.
Paddle shafts generally define solid or tubular, elongated forms with a uniform outer diameter along the length of the paddle shaft. The uniform outer diameter of the paddle shaft can result in uniform flexural rigidity and therefore a uniform deflection which, in turn, results in most of the bending nearest the lower hand (fulcrum) and uniformly diminishing bending toward the distal end. Such a configuration yields less flexibility and responsiveness, and therefore limits the potential energy invested into each stroke. Excessive user strength is needed to bend a uniform diameter solid or tubular shaft for the purpose of loading substantial potential energy, and excessive user strength is further needed to control the potential energy release in a way to propel themselves forward.
Some paddle shafts can include tubular telescoping sections to provide adjustment in overall length. However, telescoping paddle shafts generally cannot support the high bending required to significantly flex the shaft because, each of the telescoping joints creates a step change in flexural rigidity which results in localized bending deflections exceeding the flexural properties of the material of fabrication. As such, the telescoping paddle shaft can structurally fail when attempting to load potential energy through flexure.
Pusher tips can wear out with use. Although pusher tips are generally fabricated from an elastomeric material to grip the ground surface during use, this attribute causes the pusher tip to abrade and wear over time. The connection of the pusher tip and the distal end of the paddle shaft can be facilitated with a male threaded rod at the distal end of the paddle shaft and a female threaded pusher tip insert. For a right-hand threaded rod, pushing off from one side tightens the connection between the threaded rod and the insert, while pushing off from the other side loosens the connection, resulting in the potential for the pusher tip to disconnect from the distal end of the paddle shaft.
Taping the threads to improve the tightening interference between the threaded rod and female threads of the insert, or any other means of thread locking, can result in a connection that is too tight for disconnecting in the future. Some pusher tip systems can include a pusher tip insert acting as the connecting element between the distal end of the paddle shaft and a threaded rod of the pusher tip. However, if the force to loosen the threaded rod of the pusher tip is higher than the breaking force of the adhesive bond between the insert and the distal end of the paddle shaft, the act of unscrewing the pusher tip from the insert can loosen the insert relative to the paddle shaft.
Thus, a need exists for pusher tips that can accommodate improved flexibility and control, and support reactive bending moment on a paddle shaft. A further need exists for paddle shafts that can accommodate easy and comfortable flexure for storing and returning potential energy for a stroke. A further need exists for pusher tip inserts that maintain their position within the distal end of the paddle shaft during use and further maintain a tight interference with a threaded rod of a pusher tip to resist separation between the pusher tip and the paddle shaft during use. These and other needs are addressed by the pusher tips and associated systems of the present disclosure.